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MCD - Metabolism > Protein Structure > Flashcards

Flashcards in Protein Structure Deck (19):
1

Concept of primary protein structure

Linear sequence of amino acids that make up the protein

2

Concept of secondary protein structure

Local structural motifs within a protein, dictated by primary structure

3

Concept of tertiary protein structure

The arrangement of secondary structure motifs into domains

4

Concept of quaternary protein structure

The 3D structure of multimeric proteins composed of several subunits

5

The type of reaction by which Amino Acids are joined together

Condensation

6

Trimeric peptide sketch with amino terminus, carboxyl terminus and side chains

3 amino acids joined together, NH2 = amino terminus, COOH = carboxyl terminus, R1/R2/R3 side chains

7

A-helix distinguishing features

Helical shape
N-H from one residue forming H bond with C=O 4 residues later.
Side chains project outwards
Proline will cause a kink - loses NH2 so no H bond formed.

8

B-pleated sheet distinguishing features

Sheet shape made of beta strands
N-H, C=O point out at right angles to the backbone
H bonds form between N-H and C=O of differing strands
Alternate strands running parallel = parallel sheet
Alternate strands running anti-parallel =
Anti-parallel sheet

9

Bonds responsible for holding together secondary structure?

H-bonds

10

Bonds responsible for tertiary structure

Covalent bonds
Hydrogen bonds
Ionic interactions
Van der Waals forces
Hydrophobic interactions

11

Covalent bond features

Strongest bonds
Exist in backbone
Exist between cysteine side chains - disulphide bridges.

12

Hydrogen bond features

Occur between electronegative species and hydrogen atoms
Occur between sidechains, sidechains and water, or sidechains and the backbone itself

13

Ionic interactions features

Electrostatic attraction between charged side chains. Mostly on surface of proteins, hydrophilic

14

Van der waals forces features

Weak
Electrostatic forces
Based on fluctuating electron clouds

15

Hydrophobic interactions features

Hydrophobic side chains placed next to each other in the hydrophobic core of the protein. Creates hydrophobic core and hydrophilic surface.

16

Principle of electrophoresis

AAs have charged side chains, electrophoresis can separate proteins on basic of overall charge and/or molecular weight

17

Why can proteins with single mutations be separated by electrophoresis?

Single amino acid change
Weight and/or charge changes.
Change detectable as a difference in the distance the two proteins travel under electrophoresis.

18

What is an example of N-linked glycosylation?

Addition of sugar groups to asparagine (N) residues of Luteinizing Hormone Receptor

19

Why does N-linked glycosylation have an effect on electrophoresis distance?

Mutation of two asparagine to glutamine can be picked up by electrophoresis as a reduction in the overall molecular weight of LHR.